The intranuclear transformation of estrogen receptor complexes of the rodent at the uterine, hypophyseal, and hypothalamic levels will continue to be studied. The maturational and variable physiologic states of the animal will be examined as factors involved in previous observations that dissimilar estrogen target tissues differ in their processing of the steroid-receptor complex. The development of hypophyseal responsivity to hypothalamic influences superimposed on a changing steroidal milieu will also be assessed. These efforts will entail use of both pre- and post-pubertal rodents.